Which 2007 Microsoft Office system program are you using?

Access

Excel

Double-click the cell in which you want to overtype text, and then press INSERT or INS to turn on or off the overtype mode.

Note: The Allow editing directly in cells check box must be selected (it is selected by default). To select or clear this check box, click the Microsoft Office Button
, then at the bottom of the dialog, click Excel Options, and then in the left pane, click Advanced. The check box is under the Editing options section.